Guido M.H. Knippels

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The ability of electron microscopes to analyze all the atoms in individual nanostructures is limited by lens aberrations. However, recent advances in aberration-correcting electron optics have led to greatly enhanced instrument performance and new techniques of electron microscopy. The development of an ultrastable electron microscope with(More)
We report subpicosecond electro-optic measurements of the length of individual relativistic electron bunches. The longitudinal electron-bunch shape is encoded electro-optically on to the spectrum of a chirped laser pulse. The electron-bunch length is determined by analyzing individual laser-pulse spectra obtained with and without the presence of an electron(More)
Subpicosecond synchronization between a mirror-dispersion-controlled 10-fs Ti:sapphire laser and the Free-Electron Laser for Infrared Experiments has been achieved. The measured intensity cross correlation between the two lasers is consistent with a jitter of only 400 fs rms. The wide and continuous tunability of the free-electron laser (FEL; 4.2-300mum)(More)
We have studied vibrational spectra of thin films of copper phthalocyanine and fullerene of different thicknesses on silver obtained by a visible-infrared sum-frequency generation (SFG). The free electron laser FELIX was used as a source of broadband infrared and the pulsed Nd:YLF laser system as a source of visible radiation. Excitation of a surface(More)
We present a method for the remote generation of a transient near-®eld probe using conventional IR microscopy optics. Photo-induced re ̄ectivity generated by picosecond pulses of visible light incident on the surface of a semiconductor substrate is used to create transient mirrors with dimensions determined by the spot size of the visible light. The IR(More)
A simple experimental method has been sources for the creation of short THz pulses, such as the developed to determine the shape of repetitive free electron laser and the mode locked p-Ge laser, picosecond THz pulses in the presence of jitter in the however, do not rely on optical pumping. The use of a trigger signal. This method, a modification of the(More)
Phase-matched second-harmonic generation is obtained in various LiInS(2) crystals by use of the tunable picosecond output of the free-electron laser for infrared experiments (FELIX) as the pump source in the mid-IR range from 2.75 to 6.0 microm. Deviations from the phase-matching curve calculated from Boyd's refractive-index data are observed. Furthermore,(More)
X-ray structural analysis, nuclear magnetic resonance, optical spectroscopy and second harmonic generation were used to characterize the new nonlinear crystals LilnS2 and LiInSe 2 which possess maximum band gap (3.59 and 2.86 eV at 300 K, respectively) among ternary chalcogenides. As grown crystals are only slightly colored while color change after(More)
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